[avalanche] Remove unecessary timeout in the abc_p2p_getavaaddr.py test

Summary: I noticed the test sometimes fails due to some timeout on the addnode call, which is unrelated to the test:https://build.bitcoinabc.org/viewLog.html?tab=buildLog&logTab=tree&filter=debug&expand=all&buildId=390761&_focus=3753&guest=1 . In general there is little advantage to use short timeouts as it can make the test flacky on slow machines, which doesn't help in detecting the actual issues.

Test Plan:

./test/functional/test_runner.py abc_p2p_getavaaddr

Reviewers: #bitcoin_abc, sdulfari

Reviewed By: #bitcoin_abc, sdulfari

Subscribers: sdulfari

Differential Revision: https://reviews.bitcoinabc.org/D11477